Heat oven to 450°F. Cut 4 (12x12-inch) sheets of heavy-duty foil. Place 1 chicken breast in center of each. Top each with 1 tablespoon dressing, 1 slice of tomato and 3 sage leaves.
Wrap each packet securely using double-fold seals, allowing room for heat expansion. Place packets on ungreased cookie sheet.
Bake 20 to 25 minutes or until juice of chicken is no longer pink when center of thickest pieces are cut and thermometer inserted in center reads 165°F. Carefully open packets to allow steam to escape.